Apache Commons FileUpload before 1.5 does not limit the number of request parts to be processed resulting in the possibility of an attacker triggering a DoS with a malicious upload or series of uploads. Note that, like all of the file upload limits, the new configuration option (FileUploadBase#setFileCountMax) is not enabled by default and must be explicitly configured.
https://www.debian.org/security/2023/dsa-5522
https://security.gentoo.org/glsa/202305-37
https://lists.debian.org/debian-lts-announce/2023/10/msg00020.html
https://lists.apache.org/thread/4xl4l09mhwg4vgsk7dxqogcjrobrrdoy